我有一个meme命令，它从subreddit获取一个url，然后将其设置为嵌入图像。这是我的密码：

memes = reddit.subreddit("memes")
memes_subs = []
memes_hot = memes.hot(limit = 50)

for submission in memes_hot:
  memes_subs.append(submission)

@client.command()
async def meme(ctx):
  random_sub = random.choice(memes_subs)
  name = random_sub.title
  url = random_sub.url

  em = discord.Embed(title = name, color = 0xfdcb58)
  em.set_footer(text = f"Requested by {ctx.message.author} | From r/memes")
  em.set_image(url = url)

  await ctx.send(embed = em)

有时嵌入没有图像，或者图像根本无法加载。我不知道为什么会发生这种情况，所以任何洞察将不胜感激。